The instant invention relates to expanding plug gage heads, and more particularly to an actuator and programmable amplifier for actuating an expanding plug gage head and amplifying a dimension sensed by the gage. The sensed dimension is displayed on a digital liquid crystal display.
Expanding plug gage heads and amplifiers therefore have heretofore been known in the art. In this regard, a variety of different expanding plug gage heads are available for measuring both inner diameter and outer diameter dimensions. An expanding plug gage head includes a split and expandable gage body formed with an enlarged workpiece engaging end and an integral hinge. A plunger having a tapered conical end is received through the gage body so that the tapered end engages with an internal socket adjacent the workpiece engaging end of the gage body. Axial movement of the plunger within the gage body causes the cone tipped end to engage with the internal socket thereby expanding or contracting the workpiece engaging end. The opposite end of the plunger is formed with a T-shaped bayonet for coupling to an actuator/amplifier device. The prior art actuator/amplifier devices are purely mechanical in nature and they include a spring-loaded slotted lever to which the bayonet end of the plunger is connected for retracting the plunger and contracting the gage head. The prior art actuator/amplifiers further include a series of levers and gears which respond to the axial displacement of the plunger and magnify the motion. The measured dimension is displayed on a circular indicator dial on the actuator/amplifier unit. The indicator dial has a mid-point representing a standard measurement wherein movement of the indicator hand to the left or right of the mid-point indicates a +/- deviation from the standard measurement. Gage heads and amplifier devices are typically offered in a choice of many different amplification factors in both English and Metric measurements. For example, Comtorgage Corporation of Slatersville, R.I. manufactures a series of gage heads and amplifiers having an amplification system comprising at least eight different amplification factors, i.e. CM1, CM2, CM3, CM4, CM6, CM8, CM10 and CM14. The different amplification factors are accomplished by varying the angle on the tapered conical end of the plunger. The internal gears and levers of the amplifiers do not change, but the different amplifications are reflected on the indicator dial of the amplifier which has a graduated deviation scale corresponding to the angle of the plunger. Accordingly, an expansion plug having a particular amplification factor must be matched to an amplifier having the corresponding scale on the indicator dial. While the mechanical amplifiers are extremely accurate in producing true measurements, there are two significant drawbacks. Firstly, the user must maintain a set of amplifiers for each amplification system because the gage heads are offered in different amplification scales. Furthermore, in the mass production of machined parts, it is often necessary to keep detailed records of deviation from standard measurements in order to improve or alter machining processes to produce more accurate parts. Since it is not possible to connect the mechanical amplifiers to any kind of electronic monitoring system, the measurements must be recorded by hand. Hand recording is extremely time consuming and is prone to human error.
In this regard, a coupler which is adapted to connect an expanding plug gage head with an electronic display device and data collector is disclosed in the U.S. Pat. No. to Meyers 4,604,809 which represents the closest prior art to the subject invention of which the applicant is aware. The coupler comprises a series of levers that convert the linear displacement of the plunger to a 1:1 ratio where contact is made with an electronic transducer. The transducer electrically relays the position of the plunger to an electronic indicator device. The electronic indicator system allows repeated measurements to be recorded in a data collector for later analysis. The coupler and electronic indicator therefore eliminates the problem of recording measurements. However, since the transfer levers in the coupler are designed to convert the axial displacement of a particular angle on the cone tip of a plunger and each different amplification system has its own unique angle, a different coupler device is required for each amplification system. As is the case with the mechanical amplifiers, the expansion plug must be matched with a particular coupler to produce a true measurement. Since gage heads are typically produced in eight different magnification systems, an operator of the electronic recording system must keep on hand eight different coupler devices.
The instant invention provides an actuator and programmable amplifier which is operative for use with a plurality of different gage heads having a plurality of different amplification factors, and which provides a means for inputting and storing different gage head configurations. The actuator/amplifier of the instant invention includes a housing having a retracting lever pivotably mounted therein. The cross head end of the plunger of the gage head is releasably received and secured through a slot in the retracting lever. A compression spring normally urges the retraction lever and plunger to a first position wherein the plunger is fully extended within the gage head. The retracting lever is pivotably actuatable for withdrawing the plunger so that the tapered working end of the plunger is at least partially retracted from the gage head. The actuator/amplifier device further includes a transducer having a core which is coupled to the crosshead end of the plunger. The transducer is operative for measuring an axial position of the plunger within the gage head. The programmable actuator/amplifier still further includes a memory for storing a set of configuration data for each of a plurality of different gage heads. Each set of configuration data includes a predetermined measuring dimension of the gage head, a predetermined amplification factor of the tapered operating end of the plunger of the gage head and several other data elements. The actuator/amplifier further includes a key pad for inputting the configuration data to the memory and for selecting one of the sets of configuration data from the memory. A central processor converts the sensed axial position of the plunger to a measured dimension according to the selected set of configuration data and outputs the measured dimension to a digital liquid crystal display.
Accordingly, it is an object of the instant invention to provide an actuator for an expanding plug gage head which is operable with a plurality different gage heads having different amplification factors.
It is another object to provide a programmable amplifier for an expanding plug gage head which is operable for amplifying the motion of gage heads having a plurality of different amplification factors.
It is another object to provide a programmable amplifier for expanding plug gage heads which provides means for inputting and storing a plurality of different gage head configurations.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.